classdef spyfilt_diffx < spyview_filter
   properties (Constant=true)
       name='dZ/dx';
       description='Take a derivative along horizontal line';
       parameters=[];
   end
   methods
       function [pm,px,py]=filter(sf,pm,px,py)
           pm=diff(pm,[],2);
           px=(px(1:(end-1))+px(2:end))/2;
       end
   end
end